'Data List' Editor (Safety PLC)
The following information refers to a specific, typical device type. Your screen may differ.
This help topic describes the 'Data List' editor of the 'Safety PLC' PLANT node.
This topic contains the following sections:
Content of the Safety PLC Data List
The Safety PLC node represents the safety-related runtime. The list contains:
- All resource-global
variables of the Safety PLC (safety-related and standard) according to the IEC 61131-3 standard.
- Variables of the standard controller that are already connected to a Safety PLC variable (standard data type).
- All process data items (I/O terminals) that are already connected to a Safety PLC variable.
- All HMI tags of all HMI pages in the project that are already connected to a Safety PLC variable.
Note
In the Data List of the Safety PLC, HMI tags can only be created for exchange variables. |
Functions of the Safety PLC Data List
The Data List of the Safety PLC node is a tabular editor with the following functions:
- Display and editing the global IEC variables (standard and safety-related) of the Safety PLC.
- Creation of new global IEC variables (standard and safety-related) for the Safety PLC.
- Assignment (role mapping) of data items of the different engineering disciplines.
- Import data items from a .csv file and export data items to a .csv file.
Further Info
Further information on the 'Data List' editor and how to use it, can be found in the topic "Data Lists". |
Toolbar of the Safety PLC Data List
Click here to show the toolbar description
Note
In Data Lists, the selection in drop-down lists is done with a single-click, not with a double-click. |
Toolbar button | Description |
 | Moves the selected variable(s) or variable group up or down. |
 | Collapses/expands all variable groups. The arrow icon in front of the group name shows whether a variable group is expanded or collapsed.
: Group expanded.
: Group collapsed. |
 | Creates a new global variable in the current Data List. |
 | Creates a new variable group. The new group is created above the group containing the table line that you have selected previously. |
 | This button is only available, for Safety PLC variables of a standard (non-safety-related) data type which are not yet assigned to a standard controller variable.It creates a new controller variable for the selected variable in both Data Lists (controller and Safety PLC) and inserts it into the respective column 'Variable (PLC)'. |
 | This button is only available, for Safety PLC variables of a standard (non-safety-related) data type which are assigned to a standard controller variable.Deletes the variable and its assignments from the current Data List. |
 | The command is only available if two table entries are selected that can be connected to each other and while the debug mode is not active.Connects the selected list entries. |
 | Deletes the assignment of process data item and variable in the selected table line. |
 | This command is only available for variables which are assigned to a controller variable (exchange variables).Deletes the assignment of the selected Safety PLC variable to the controller variable. The disconnected controller variable is not deleted. |
 | The command is available for variables which are connected to at least one other role.It is also useable for multiple mappings (e.g., threefold mapping between controller variable and Safety PLC variable and process datum).Deletes all assignments in the selected table row. The disconnected variable is not deleted. |
 | Removes all unused global variable declarations of the Safety PLC from the Data List. Unused means that the variable or instance is declared but not used in the code of any POU. The number of removed variables is shown in the Message Window. |
 | Imports data items from a .csv file (semicolon-separated values) to the Data List. The progress of the import is displayed in the MESSAGES window. The log entries provide, amongst other, information on the number of imported process data items, variables, HMI tags, etc.Observe the following when importing data items:
- Only variables and HMI tags are imported. Process data items assigned to variables are not imported.
- The data items are imported into the pool of data items (contains the data items of all Data Lists). This means data items which do not belong to the active Data List are also imported and added to the respective Data List.Example: If the .csv file contains safety-related variables and you perform the import in the Data List of the controller node (contains only variables of the standard controller), the safety-related variables are imported into the Data List of the Safety PLC node.
- Existing data items are not overwritten or modified. Only those data items are imported which are not yet contained in the Data List.
- Data items with invalid properties, for example, invalid data types are imported but marked as errors in the Data List (a corresponding entry is also shown in the MESSAGES window).
- Data items with invalid variable names are not imported and the process is aborted.
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 | Exports all data items contained in the active Data List to a .csv file.The progress of the export is displayed in the MESSAGES window. The log entries provide, amongst other, information on the number of data items exported.
Note
If you edit the exported csv file with an external tool, you must make sure that the editor used does not change the column separators (semicolons) or the file encoding. For example, MS Excel may be set to modify csv files so that they cannot be reimported. |
|
 | Opens the 'Init Value Configuration' editor below the Data List table where members of user-defined data types (ARRAYs and STRUCTs) can be initialized. After selecting the declaration line of the user-defined data type in the variables table, its members can be edited in the grid of the 'Init Value Configuration' editor. |
 | Opens the toolbar for local find and replace operations. |
Columns in the Data List
Click here to show the description of the Data List columns (each column represents one data item property)
Column | Property | Meaning |
Variable (Safety PLC)This column and its properties are only available if a Safety PLC is used in your project. | Expand the column by clicking the icon in the column header to display further properties. | Identifier of the safety-related global IEC variable. |
Type | Data type of the variable. The data type determines what kind of value the variable can have and it defines the initial value, range of possible values and the number of bits.Left-clicking into the cell shows the selectable data types represented by a corresponding symbol and the data type name. |
Usage | Keyword that defines the scope of the variable. In the Data List of the controller, only 'Global' is available for declaring resource-global variables which can be used in all POUs of the related resource. |
I/Q/M | Data direction of the variable. This property is only available for Safety PLC variables (of both standard and safety-related data types).
- M = variable is marker variable. It is neither connected to a device input/output nor it is used as exchange variable.
- I = variable can be read by the safety-related application. It can be connected to an input process data item or it can be used as "incoming exchange variable" which is written in the standard (non-safety-related) application.
- Q = variable can be written by the safety-related application. It can be connected to an output process data item or it can be used as "outgoing exchange variable" which is read in the standard (non-safety-related) application.
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Comment | User-defined comment. The input is limited to 128 characters. |
Init | According to IEC 61131-3, initial values can optionally be assigned to variables. This means that a variable which is going to be used for the first time in the controller program is used with its initial value.The initial value has to fit to the selected data type. |
Confirm | The 'Confirm' flag is active and must be selected under the following circumstances:
- Each time you assign a process data item to a safety-related variable (thus defining a safety-related input or output variable).
- Each time a process data item which is assigned to a safety-related variable was modified in the PLANT.1
PLCnext Engineer reports a warning message in the Safety Log (MESSAGES window) as long as 'Confirm' is not selected for all safety-related I/O variables.The 'Confirm' flag is automatically deselected after replacing a safety-related module. In this case, you must repeat the I/O verification and set 'Confirm' again for the affected variables. Observe the hazard message and information given in the topic "Replacing Devices", section "Safety requirements when replacing the Safety PLC...". |
Variable (PLC) | Expand the column by clicking the icon in the column header to display further properties. | Identifier of the global IEC variable. |
Type | Data type of the variable. The data type determines what kind of value the variable can have and it defines the initial value, range of possible values and the number of bits.Left-clicking into the cell shows the selectable data types represented by a corresponding symbol and the data type name. |
Usage | Keyword that defines the scope of the variable. In the Data List of the controller, only 'Global' is available for declaring resource-global variables which can be used in all POUs of the related resource. |
Comment | User-defined comment. The input is limited to 128 characters. |
Init | According to IEC 61131-3, initial values can optionally be assigned to variables. This means that a variable which is going to be used for the first time in the controller program is used with its initial value.The initial value has to fit to the selected data type.
Note
Variables which are assigned to physical inputs cannot be initialized. |
Note
If you are using PLCnext Engineer in another user interface language and/or with another Windows system locale than English you must enter numeric values with a '.' as decimal separator (always according to the English standard). This applies, for example, when entering initial values in variables tables or REAL/LREAL literals in the code. |
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Retain | Specifies that a retentive variable is declared. The value of a retentive variable is kept in the controller memory even if power is switched off. In case of a warm start, the last value of the variable is going to be used.The 'Retain' attribute is not allowed in combination with the 'Constant' attribute and vice versa.Also refer to the topic "Retain Handling" for further information. |
Constant | Declares a constant variable (VAR_CONSTANT acc. to the IEC 61131-3). The value of a constant variable cannot be changed by the running application (read-only access). See the topic "Constant Variables" for further information. |
OPC | Specifies that the variable is visible for the integrated OPC UA server and can therefore be subscribed by OPC clients.
Note
This attribute is not relevant for the OPC UA PubSub communication. Global variables can be added to a PubSub data set even if the checkbox is not selected. |
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Process data item | Expand the column by clicking the icon in the column header to display further properties. | Identifier of the process data item. |
I/Q | Indicates the data direction of the process data item:
- I = Input process data which can be read by the application program.
- Q = Output process data which can be written in the application program.
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Type | Data type of the process data item (field bus data type). |
Offset | Indicates the bit offset of the process data item from the start address of the communication packet for this device/module. |
1 | After modifying the PLANT structure by adding, deleting or replacing devices, the following applies: |
Unintended equipment operation
- Inspect and correct as necessary any global I/O variables related to physical, safety-related I/Os whenever you modify the PLANT structure.
- Whenever you add, delete or exchange devices in the PLANT, validate the physical wiring of your safety-related architecture and thoroughly test the application.
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What do you want to do?
Assign data items in Data Lists
Create exchange variables
Remove assignments (disconnect)
Create an HMI tag in a Data List
Manage global variables in a Data List
Refactor variables
Initialize ARRAY or STRUCT members using the 'Init Value Configuration' editor
Import/export data items from/to a .csv file
Filter & Sort the Data List